The present invention relates to an oily base for a cosmetic comprising an ester compound made from a multivalent alcohol and a fatty acid, and a cosmetic comprising the same, more specifically to an oily base for a cosmetic comprising an ester compound made from dipentaerythritol and a fatty acid having 5 to 16 carbon atoms, a cosmetic comprising the same, and a process for the preparation of the said ester compound.
In the prior art, various ester compounds are known as an oily base used in various cosmetics.
Document 1*1 discloses a liquid ester composition obtained by esterifying dipentaerythritol with a branched type isostearic acid indicated by the chemical formula R—C(COOH)H—(CH2CH2)—R, wherein R represents a branched hydrocarbon having 7 carbon atoms, characterized in that a viscosity of the composition at 25 degrees C. is 100,000 to 2,000,000 mPa·s, a hydroxyl value of the composition is 10 to 160, and a clouding point of the composition is less than 5 degrees C. The aforesaid liquid ester composition is obtained by reacting dipentaerythritol with stearic acid, which has 18 carbon atoms, having a particular branched structure. The aforesaid liquid ester composition exhibits excellent cosmetic film-holding ability and provides a cosmetic film having a gloss and moisturizing feeling comparable to polybutene which has been usually used in a cosmetic. In addition, the composition exhibits pigment-dispersing ability and water-holding property which polybutene does not have. Upon blending the aforesaid liquid ester composition in a make-up cosmetic, the effect is exhibited that the makeup cosmetic exhibits excellent cosmetic film-holding ability.
Document 2*2 discloses an oily cosmetic comprising (A) a liquid ester composition obtained by esterifying a branched type isostearic acid represented by the general formula R1—C(COOH)H—CH2CH2—R2, wherein R1 and R2 represent a branched hydrocarbon radical having 7 carbon atoms and may be the same or different from each other, and (B) a silicone resin. As component (A), mention is made of dipentaerythrityl pentaisostearate, dipentaerythrityl tetraisostearate, dipentaerythrityl triisostearate, glyceryl triisostearate and diglyceryl triisostearate. As component (B), trimethylsiloxysilicic acid and perfluoroalkyl-polyalkylsiloxysilicic acid are mentioned. The invention described in Document 2 provides an oily cosmetic having comfortable feeling and good gloss when the cosmetic is applied, and excellent moisturizing feeling-holding ability and excellent cosmetic effect-holding ability.
Document 3*3 discloses a cosmetic for lips comprising (A) a fluorine-polyether co-modified silicone and (B) a liquid ester composition obtained by esterifying dipentaerythritol with a branched type isostearic acid represented by the general formula R6—C(COOH)H—CH2CH2—R7, wherein R6 and R7 represent a branched hydrocarbon radical having 7 carbon atoms and may be the same or different from each other, wherein a viscosity at 25 degrees C. of the liquid ester composition is 100,000 to 2,000,000 mPa·s, a hydroxyl value of the liquid ester composition is 10 to 160, and a clouding point of the liquid ester composition is less than 5 degrees C. The ester composition of component (B) is the same as the ester composition described in Document 1. By blending a combination of the aforesaid component (B) with the aforesaid component (A) in a cosmetic for lips, the invention described in Document 3 gives excellent pigment-dispersing ability, excellent comfortable feeling on use and gloss when the cosmetic is applied, excellent moisturizing feeling-holding ability and excellent cosmetic effect-holding ability to the cosmetic for lips.
All the inventions described in the aforesaid Documents 1 to 3 use the composition wherein isostearic acid, which has 18 carbon atoms, having a particular branched structure is esterified. The resultant liquid ester composition has extremely high viscosity, which causes the problem that uncomfortable sticky feeling appears on the skin upon blending the composition in a skin-care cosmetic. Furthermore, another problem occurs, that is, the use of such a special substance raises the preparation cost.
Document 4*4 discloses an oily composition for the skin comprising a co-enzyme represented by a particular formula and a medium chain fatty acid ester obtained by esterifying a medium chain fatty acid having 6 to 12 carbon atoms with a branched multivalent alcohol, and being free from water. The invention described in Document 4 provides an oily composition for the skin wherein the co-enzyme is able to be homogenously dissolved without crystallization or aggregation when the composition is prepared, having no problem in the safety to the skin and the stability, exhibiting good feeling on use when the composition is applied to the skin, and being highly effective to improve taut skin, wrinkle and sag. As the branched multivalent alcohol, mention is made of neopentyl glycol, pentaerythritol, dipentaerythritol, trimethylolpropane, ditrimethylolpropane and isopentyl glycol. There is a description that the particularly preferable branched multivalent alcohol is neopentyl glycol. As the medium chain fatty acid having 6 to 12 carbon atoms, mention is made of hexanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid and 2-ethylhexanoic acid. In the Examples, as the medium chain fatty acid ester, only neopentyl glycol didecanoate, neopentyl glycol di2-ethylhexanoate and pentaerythrityl tetra2-ethylhexanoate are used.
The documents cited above are as follows: *1 Document 1: WO 2006/3992 leaflet;*2 Document 2: Japanese Patent Application Laid-Open 2006-111,543;*3 Document 3: Japanese Patent Application Laid-Open 2006-45,102;*4 Document 4: Japanese Patent Application Laid-Open 2007-84,505.